Beat the sugar well with 1 ½ cups of butter. Add the egg and milk, vanilla, sifted flour, and baking powder. Set aside.
Separately, mix the ½ cup of butter with the cinnamon and light brown sugar. Pour this mixture into the bottom of the mold.
You can use the Instant Pot removable round bake pan for this.
Spread the peaches out on the mold and pour the mixture on top.
Put the mold in the pot on the rack and add 1 ½ cups of water.
Close and lock the Instant Pot® lid. Make sure the steam release handle is turned to Sealing. Press Pressure Cook, pressure level High, and set time to 40 Minutes .
Once the time is up, leave inside the pot for 1 Hour so that it releases the steam naturally and it cools down inside the pot.
Remove, unmold, and serve. Optional to brown, put under the oven grill for 10 Minutes.